Interview the user relentlessly until you reach a shared understanding. Map this as a design tree: every decision branches into the decisions that hang off it.
Work the tree in rounds. The frontier is every decision whose prerequisites are already settled: the questions you can ask now without guessing at answers you haven't heard yet. Ask the whole frontier in one round: number each question and give your recommended answer. Then wait for the user's answers before the next round.
Format a round like so:
❓ **Q1** - **<question title>**: <question body, might be multiple paragraphs, including multiple choices>
➡️ <your recommended answer>
---
❓ **Q2** - **<question title>**: <question body, might be multiple paragraphs, including multiple choices>
➡️ <your recommended answer>
Each round the user answers reshapes the tree: settled decisions push the frontier outward and unblock questions that depended on them. Recompute the frontier and ask the next round. A question whose answer depends on another question still open in this round belongs to a later round, not this one.
Finding facts is your job, never the user's. When a frontier question needs a fact from the environment (filesystem, tools, etc.), dispatch a sub-agent to find it; don't ask the user for anything you could look up yourself. Don't block on it: a running exploration is an unsettled prerequisite, so only the questions downstream of it wait for the sub-agent to report; ask the rest of the frontier now. The decisions are the user's: put each to them and wait.
The session is done when the frontier is empty: every branch of the design tree visited, nothing left silently assumed. Do not act on it until the user confirms you have reached a shared understanding.
In AOS
This is the primitive. Two skills compose it, and neither duplicates it:
grill-me— the interview alone. Use without a working directory, or when the output is a decision rather than a document.grill-with-docs— the interview plusdomain-modeling, leaving a paper trail. Prefer it whenever there is a repo to leave one in.
Grilling produces a shared understanding, not a plan. Once the frontier is empty, hand off to whichever pipeline the work actually needs — /startcycle for a straight run, /startcycle-graph when the durable record and repair loop earn their overhead, /startcycle-graph-user for a throwaway fan-out. /bdbrainstorm and /bdbmediastorm invoke this skill as their own interview step rather than restating it.
Do not use the AskUserQuestion tool for a grilling round. A round is numbered questions with recommended answers, answered in prose, in whatever order the user likes — several at once, or one with a correction to another. Forcing that into fixed-choice widgets loses exactly the nuance the interview exists to surface.